Swaged tri-flow muffler

ABSTRACT

A swaged outer muffler shell with straight or offset bushings houses a three tube structure forming a tri-flow gas passage through the muffler.

United States Patent 1191 1111 3,841,435

Hetherington I 1 Oct. 15, 1974 [54] SWAGED TRl-FLOW MUFFLER 2,656,005l0/l953 Cary l8l/57 X 3,141,518 7/1964 11611111 181/35 c ux [75]Inventor Theomre nehermgmn Jackson 3,191,715 /1965 Jettinghoff 181 61 xMlch- 3,209,861 10/1965 Whitney 181/35 c ux 3,340,957 9/1967 Vautaw ct21L. [81/36 D UX [73] Asslgnee' Tenneco Racme 3,710,892 1/1973 Hubbcll181/54 [22] Filed: Nov. 12, 1973 21 Appl. No.2 415,284

Primary ExaminerR1chard B. W1lk1nson Related Appllcauon Dam AssistantExaminer-John F. Gonzales [63] Continuation-impart of Ser. No. 329,395,Feb. S, Attorney, Agent, or Firm-Harness, Dickey & Pierce I973,abandoned.

[521' US. Cl 181/54, 29/157 R, 181/35 C,

, 181/61 51 1111. C1. F01n 1/08 [57] ABSTRACT [58] Field of Searchl8l/35 C, 49, S3, 54, 57,

1531 59 1; 29 157 R, 475 A swaged outer muffler shell with straight oroffset bushings houses a three tube structure forming a tri- 5References Cited flow gas passage through the muffler.

UNITED STATES PATENTS 2,357,791 9/1944 Powers 181/54 Quinsgl llrgyingfigures 47 X X 5/ 17 x ,7! r; 66 x -ooo X a? 41 x 1; g 11/): J; A;

PAIENIEDUBT 1 5l914 SHEET 1 BF 2 RELATED APPLICATION This application isa continuatiomin-part of my copending US. application, Ser. No. 329,395,filed Feb. 5, I973, now abandoned and assigned to the assignee hereof.

BRIEF SUMMARY OF THE INVENTION DESCRIPTION OF THE DRAWINGS FIG. 1 is alongitudinal cross section through a muffler embodying the inventionwith the various tubes rotated into the plane of the section;

FIG. 2 is an end view of the muffler of FIG. 1 and showing the actuallocation of the tubes;

FIG. 3 is a longitudinal cross section through a second embodiment ofthe invention; and

FIG. 4 is an end view of the muffler of FIG. 3.

In the drawings, the symbol x designates a spotweld.

DESCRIPTION OF THE INVENTION The muffler 1 comprises an outer shell 3which is originally a seamless steel tube but which is swaged down atopposite ends to form reduced diameter inlet and outlet bushings 5 and7, respectively. The inner ends of the bushings are preferably coaxialwith the main, full diameter body 11 of the shell but, preferably, andas illustrated, the bushings are angled or offset in opposite directionsa slight but equal amount to facilitate a neat installation in theexhaust system of a partic- "ular make automobile manufactured outsidethe United States. The shell is reduced down into the bushings after atube and partition subassembly 13 is inserted.

The subassembly 13 comprises three longitudinally separated partitionsI5, 17, and 19 which have annular peripheral flanges 21 that lit theinside surface of the shell main body portion 11 but are preferably notspotwelded or otherwise affixed to the shell whereby relativelongitudinal adjustment between the partitions and shell may occur.Partition 15 has three openings as defined by necks 23, 25, and 27 andthese are longitudinally aligned with three openings in partition 17 asdefined by necks 29, 31, and 33. Partition 19 has two openings asdefined by necks 35 and 37, and these are longitudinally aligned withnecks 31 and 33 in partition 17. Imperforate open ended tube 39 issupported in and spotwelded to necks 23 and 29; perforate open endedtube 41 is supported in necks 25 and 31, being spotwelded to neck 25;imperforate open ended tube 43 is supported in and spotwelded to neck35; and open ended imperforate tube 45 is supported in necks 27, 33, and37, being spotwelded to necks 27 and 37. It will be appreciated that byvirtue of the various weld connections between the symmetricallyarranged tubes and partitions the parts are secured to each other andmay be readily handled as the subassembly 13 for insertion into andpositioning within the shell 3 prior to formation of bushings 5 and 7.After insertion, the spotwelding of the tubes to the bushings holds thesubassembly in place. Differential expansion is accommodated by the slipfit of the partition in the shell and of tube 45 in partition 17.

The tube 39 has an offset or angled portion 47 termi nating in an inletopening 49 and the tube 45 has an offset or angled portion 51terminating in an outlet opening 53 which is coaxial with opening 49 andwith the axis of the shell 3. The end portions of the tubes definingopenings 49 and 53 serve as jig and fixture means for the swaging of theends of the shell 3 into the bushings 5 and 7, the shell being reducedin diameter into tight contact with the ends of the tubes so that thetubes and shell can be spotwelded together as indicated. After theswaging of the ends of the shell into bushings 5 and 7, the bushings canbe offset or angled in opposite directions as shown, though spotweldingof the ends of the tubes to the bushings is preferably done prior to theoffsetting.

The partitions divide the interior of shell 3 into a series oflongitudinally adjacent chambers. Thus, partition 15 and the inlet end55 of shell 3 form a chamber 57; partitions l5 and 17 form a chamber 59;partitions l7 and 19 form a chamber 61; and partition 19 and the outletend 63 of the shell form a chamber 65. Chambers 57 and 61 serve as crossover chambers and also function to provide sound attenuation; chamber 59serves as a resonator chamber for intermediate and high frequencies incombination with the perforations 67 in tube 41; and chamber 65 has avolume coordinated with the length and cross sectional area of tube 43to serve as a Helmholtz resonator for attenuating a predeterminedrelatively low frequency of sound in the exhaust system.

In operation, an exhaust pipe (not shown) is attached to the inletbushing 5 to conduct exhaust gas from an internal combustion engine tothe open end of inlet pipe 39. The gas flows from pipe 39 to chamber 61where it reverses direction to enter perforated tube 41 and flow tochamber 57. It reverses direction in chamber 57 and flows to outletbushing 7 via outlet tube 45. A predetermined low frequency isattenuated by connection of tube 43 and chamber 65 to chamber 61. Gas atthe outlet bushing 7 can flow to atmosphere via a tailpipe 67 secured tothe bushing.

The three tube arrangement is known to produce very effective silencingand the shape and size of chamber 57 is thought to increase the usualattenuation. If desired, the portions of tubes 39 and/or 45 in chamber59 may be perforated to provide acoustic communication as well as somecross bleeding for back pressure reduction.

Referring to the second embodiment shown in FIGS. 3 and 4, the muffler101 comprises an outer shell 103 which is originally a seamless steeltube but which is swaged down at opposite ends to form reduced diameterinlet and outlet bushings 10S and 107, respectively.

The inner ends of the bushings are preferably coaxial with the main,full diameter body 111 of the shell. The

shell 103 is reduced down into the bushings after a tube 2 and partitionsubassembly 113 is inserted.

The subassembly 113 comprises three longitudinally separated partitions115, 117, and 119 which have annular peripheral flanges 121 that fit theinside surface of the shell main body portion 111 but are preferably notspotwelded or otherwise affixed to the shell whereby relativelongitudinal adjustment between the partitions and shell may occur.Partition 115 has two openings as defined by necks 123 and 125, neck 123being longitudinally aligned with an opening in otherwise imperforatepartition 117 as defined by neck 127. Partition 119 has two openings asdefined by necks 135 and 137, neck 135 being longitudinally aligned withneck 127. lmperforate open ended tube 139 is supported in and spotweldedto neck 123; perforate open ended tube 141 is supported in andspotwelded necks 123, 127, and 135; and imperforate open ended tube 143is supported in and spotwelded to neck 137. The various weld connectionsbetween the symmetrically arranged tubes and partitions secure them toeach other so that they may be readily handled as the subassembly 113for insertion into and positioning within the shell 103 prior toformation of bushings 105 and 107. After insertion, the spotwelding ofone or both tubes 139 and 143 to one or both bushings holds thesubassembly in place. Differential expansion is accommodated by the slipfit of the partitions in the shell.

The tube 139 has an offset or angled portion 147 terminating in an inletopening 149 and the tube 143 has an offset or angled portion 151terminating in an outlet opening 153 which is coaxial with opening 149and with the axis of the shell 103. The end portions of the tubesdefining openings 149 and 153 may be used asjig and fixture means forthe swaging of the ends of the shell 103 into the bushings 105 and 107,the shell being reduced in diameter into tight contact with the ends ofthe tubes so that the tubes and shell can be spotwelded together asindicated. The bushings can be offset or angled as in FIGS. 1-2, ifdesired.

The partitions divide the interior of shell 103 into a series oflongitudinally adjacent chambers. Thus, partition 115 and the inlet end155 of shell 103 form a chamber 157; partitions 115 and 117 form achamber 159; partitions 117 and 119 form a chamber 161; and partition119 and the outlet end 163 of the shell form a chamber 165. Tubes 139and 145 project about halfway into the chambers 159 and 161,respectively. Tube 141 is preferably perforated along its entire lengthso that there is communication between the inside of the tube andchambers 159 and 161.

In operation, an exhaust pipe (not shown) is attached to the inletbushing 105 to conduct exhaust gas from an internal combustion engine tothe open end of inlet pipe 139. The gas flows from pipe 139 to chamber159 where it reverses direction to flow through two holes formed by twonecks 167 in partition 115 and flow to chamber 157. It reversesdirection in chamber 157 and flows to chamber 165 via intermediate tube141. The gas reverses direction in chamber 165 and flows through gaspassage means in the form of two holes (not shown) in partition 119formed by necks similar to necks 167 and flow into chamber 161. Fromthere it reverses direction to flow out of the muffler via the outlettube 143. The perforations in tube 141 permit cross bleeding fromchamber 159 into the tube and from the tube into chamber 161 therebytending to reduce back pressure.

The three tube arrangement is known to produce very effective silencingand the shape and size of end chambers 157 and is thought to increasethe usual attenuation.

It will be seen that the shells 3 and 103 with, if desired, offsetbushings, are very compact. The shell is monolithic or one piece with noseams and is therefore particularly strong and corrosion resistant. Theinternal structure provides a high degree of attenuation over a widerange of frequencies. Modifications in the specific details shown may bemade without departing from the spirit and scope of the invention.

1 claim:

1. A muffler adapted for use in an internal combustion engine exhaustsystem comprising an elongated tubular monolithic shell having oppositeends reduced in diameter to form inlet and outlet bushings respectively,a plurality of transverse partitions located inside and supported on thewall of the shell, three parallel longitudinally extending open endedgas flow tubes supported in and structurally interconnecting thepartitions so that the partitions and tubes form a subassembly, firstand second of said tubes having offset portions extending respectivelyinto said inlet and outlet bushings and being supported therein.

2. A muffler as set forth in claim 1 wherein said offset portions arewelded to said bushings and said partitions have a slip fit with respectto the shell.

3. A muffler as set forth in claim 1 wherein there are three partitionssubdividing the space inside the shell into four chambers, a first ofsaid partitions acting with the inlet end of the shell to define a firstchamber, a second of said partitions acting with the first partition todefine a second chamber, a third of said partitions acting with thesecond partition to define a third chamber, said third partition actingwith the outlet end of the shell to define a fourth chamber.

4. A muffler as set forth in claim 3 wherein at least one of the tubeshas perforations along a portion of its length that is located in saidsecond chamber.

5. A muffler as set forth in claim 4 including an open ended tuning tubemounted on the third partition and acoustically connecting the thirdchamber to the fourth chamber.

6. A muffler as set forth in claim 3 wherein said offset portions ofsaid first and second tubes are located in said first and fourthchambers respectively.

7. A muffler as set forth in claim 6 wherein said first and second tubesopen respectively into the third and the first chambers, the third ofsaid tubes opening into the first and third chambers and extendingthrough the second chamber.

8. A muffler as set forth in claim 7 wherein said third tube isperforated in said second chamber.

9. A muffler as set forth in claim 8 including a tuning tube mounted onthe third partition and connecting the third chamber to the fourthchamber.

10. A muffler as set forth in claim 9 wherein said bushings extend at anangle to the longitudinal axis of the shell.

11. A muffler as set forth in claim 3 wherein said first tube opens intosaid second chamber, said second tube opens into said third chamber, andsaid first and third partitions having gas passage means therein for theflow of gas from the second chamber to the first chamber and from thefourth chamber to the third chamber, the third of said tubes opening atone end in the first chamher and at the other end in the fourth chamberand extending through said second and third chambers.

12. A muffler as set forth in claim 11 wherein said third tube has anarray of perforations opening into at least one of said second and thirdchambers.

' 13. A muffler as set forth in claim 11 wherein said third tube isperforated and the perforations open into both said second and thirdchambers and provide means for limited bypass flow of gas between thetube and said chambers.

14. The method of making a muffler which comprises forming a subassemblyof a plurality of partitions and three parallel tubes extending betweenand welded to the partitions, one of said tubes being an inlet tube andanother being an outlet tube, said inlet and outlet tubes being bent tohave offset ends, inserting said subassembly into said shell andproviding said partitions with a slip fit on the inner wall of theshell, and swaging the ends of the shell down into bushings extendingaround and in contact with the offset ends of said inlet and outlettubes.

15. The method of claim 14 including the step of bending the bushings atangles to the axis of the shell.

16. The method of making a muffler which comprises forming a subassemblyof three partitions and three parallel tubes secured to the partitions,a first of said tubes being an inlet tube and a second being an outlettube and said first and second tubes being welded respectively to firstand second of said partitions, the third tube being welded to each ofsaid partitions, said inlet and outlet tubes being bent to have offsetends, inserting said subassembly into said shell and providing saidpartitions with a slip fit on the inner wall of the shell, swaging theends of the shell down into bushings extending around and in contactwith the offset ends of said inlet and outlet tubes, and welding atleast one of the bushings to a tube.

1. A muffler adapted for use in an internal combustion engine exhaustsystem comprising an elongated tubular monolithic shell having oppositeends reduced in diameter to form inlet and outlet bushings respectively,a plurality of transverse partitions located inside and supported on thewall of the shell, three parallel longitudinally extending open endedgas flow tubes supported in and structurally interconnecting thepartitions so that the partitions and tubes form a subassembly, firstand second of said tubes having offset portions extending respectivelyinto said inlet and outlet bushings and being supported therein.
 2. Amuffler as set forTh in claim 1 wherein said offset portions are weldedto said bushings and said partitions have a slip fit with respect to theshell.
 3. A muffler as set forth in claim 1 wherein there are threepartitions subdividing the space inside the shell into four chambers, afirst of said partitions acting with the inlet end of the shell todefine a first chamber, a second of said partitions acting with thefirst partition to define a second chamber, a third of said partitionsacting with the second partition to define a third chamber, said thirdpartition acting with the outlet end of the shell to define a fourthchamber.
 4. A muffler as set forth in claim 3 wherein at least one ofthe tubes has perforations along a portion of its length that is locatedin said second chamber.
 5. A muffler as set forth in claim 4 includingan open ended tuning tube mounted on the third partition andacoustically connecting the third chamber to the fourth chamber.
 6. Amuffler as set forth in claim 3 wherein said offset portions of saidfirst and second tubes are located in said first and fourth chambersrespectively.
 7. A muffler as set forth in claim 6 wherein said firstand second tubes open respectively into the third and the firstchambers, the third of said tubes opening into the first and thirdchambers and extending through the second chamber.
 8. A muffler as setforth in claim 7 wherein said third tube is perforated in said secondchamber.
 9. A muffler as set forth in claim 8 including a tuning tubemounted on the third partition and connecting the third chamber to thefourth chamber.
 10. A muffler as set forth in claim 9 wherein saidbushings extend at an angle to the longitudinal axis of the shell.
 11. Amuffler as set forth in claim 3 wherein said first tube opens into saidsecond chamber, said second tube opens into said third chamber, and saidfirst and third partitions having gas passage means therein for the flowof gas from the second chamber to the first chamber and from the fourthchamber to the third chamber, the third of said tubes opening at one endin the first chamber and at the other end in the fourth chamber andextending through said second and third chambers.
 12. A muffler as setforth in claim 11 wherein said third tube has an array of perforationsopening into at least one of said second and third chambers.
 13. Amuffler as set forth in claim 11 wherein said third tube is perforatedand the perforations open into both said second and third chambers andprovide means for limited bypass flow of gas between the tube and saidchambers.
 14. The method of making a muffler which comprises forming asubassembly of a plurality of partitions and three parallel tubesextending between and welded to the partitions, one of said tubes beingan inlet tube and another being an outlet tube, said inlet and outlettubes being bent to have offset ends, inserting said subassembly intosaid shell and providing said partitions with a slip fit on the innerwall of the shell, and swaging the ends of the shell down into bushingsextending around and in contact with the offset ends of said inlet andoutlet tubes.
 15. The method of claim 14 including the step of bendingthe bushings at angles to the axis of the shell.
 16. The method ofmaking a muffler which comprises forming a subassembly of threepartitions and three parallel tubes secured to the partitions, a firstof said tubes being an inlet tube and a second being an outlet tube andsaid first and second tubes being welded respectively to first andsecond of said partitions, the third tube being welded to each of saidpartitions, said inlet and outlet tubes being bent to have offset ends,inserting said subassembly into said shell and providing said partitionswith a slip fit on the inner wall of the shell, swaging the ends of theshell down into bushings extending around and in contact with the offsetends of said inlet and outlet tubes, and welding at least one of thebushings to a tube.